Activated carbon preparation fromwine production residue grapes stalk and its characterization

Activated Carbon Preparation fromWine Production Residue Grapes Stalk and Its Characterization Activated carbon, which is produced from carbonaceous materials by physical and/or chemical activation, is a carbonaceous adsorbent having unique characteristics such as high surface area, pore volume and surface chemical properties. Besidesthe cost of raw materials produced activated carbon, it is more expensive than the other adsorbents due to cost of energy and chemicals used in the processes applied for activation. Since unit operations for activation can not be changed,in orderto achieve more cost-effective active carbon, very low ornon-commercialavailability of waste materials and residues is being investigated for this purpose nowadays. In this study, activated carbon was obtained in two stages from grape stalks, wine production residue, by different physical and chemical activation methods. In the first stage, activated carbon was prepared under pure carbondioxide and nitrogen gas atmosphere at different temperatures and physical activation times. In the second stage, it was prepared from the grape stalk subjected to chemical activation by ZnCl2 at different ZnCl2/grape stalk weight ratios and for penetration times under the pure carbon dioxide and nitrogen gas atmosphere. The obtained activated carbon was characterized by ash content, elemental analysis, particle size, BET surface area, pore distribution, iodine number, Boehm titration, FT-IR, thermogravimetric and SEM analysis. In order to determine adsorption efficiency of activated carbon having the largest surface area, adsorption experiments were carried out with Cr(VI) solution. In these experiments, effects of initial solution pH, adsorbent dosage, contact time, temperature and initial Cr(VI) concentration on the Cr(VI) adsorption by activated carbon were investigated. Obtained results were applied to Langmuir and Freundlich adsorption isotherms and the Cr(VI) adsorption capacity of activated carbon obtained was calculated. According to results obtained, it has been determined that activated carbon with the best features was obtained from the grape stalk activated chemically by ZnCl2 penetrated at the ZnCl2/grape stalk weight ratio of 2 for 36 h under the pure carbon dioxide atmosphere at 700°C for 120 min carbonization times. It has been determined that the activated carbon obtained has 1411 m2/g surface area. In the adsorption study carried out with Cr(VI) solution and the activated carbon having the largest surface area (1411 m2/g), in order to remove Cr(VI) having the concentration of 100 mg/l, the most suitable pH, adsorbent dosage and contact time have been determined as pH 2.5, adsorbent dosage of 6 g/l and contact time of 30 min, respectively. Under the conditions optimized, 91.37 % Cr(VI) in the solution has been removed by activated carbon obtained from grape stalk. It has been determined that the Cr(VI) adsorption by the activated carbon fits the Langmuir adsorption isotherm and Cr(VI) adsorption capacity of the activated carbon at 25°C is 22.883 mg-Cr(VI)/g. Key Words: Activated carbon; Grape stalk; Adsorption, Activation; Surface area